There is a little program called "convert" that I use when working with MM and INCHES in the same part and I can also convert lots of other things to if I wish but I find it handy to have and hope you will to. Google "joshmadison.com/software" for it.

Here is a little diddy about units for any new users tuning in.
If you are in a part with mm units and you are given a dimension of 6 inches, instead of converting with a calculator or looking up the conversion in a table you can input the number directly as 6.in
By the same token in an inch part you can enter 12.mm and we do the conversion internally.